One of the critical molecular interactions responsible for the triggering of immune mediated mechanisms of autoimmunity is the recognition of an HLA molecule with its bound peptide antigen by a specific T-cell receptor (TCR). Our goal in this application is to determine what structural features of TCR molecules are directly responsible for mediating this recognition process. As a model system for these studies, we have chosen to focus on TCRs which interact with a specific epitope on the HLA-DRbeta1 molecule, the Dw14 epitope. The presence of this epitope, which occurs on several different DR alleles, is associated with susceptibility to rheumatoid arthritis (RA). Therefore, our studies will have specific relevance to one disease, RA, as well as general applicability to many other autoimmune disorders because of the fundamental nature of the molecular interaction studied. Our approach will be to characterize TCR genes expressed in T-cells which are either alloreactive against the Dw14 epitope, or recognize synthetic peptide antigens presented by Dw14. We will assess the significance of the selection of V genes utilized in these T-cell clones by assaying for their relative use in one way mixed lymphocyte reactions stimulated by Dw14. The significance of particular sequences within the V gene will be assessed by site directed mutagenesis, transfection into Jurkat cells, and subsequent assaying for reactivity of T-cells bearing the mutant TCRs on appropriate targets. The results of these studies should provide a detailed picture of the molecular mechanics of HLA restricted T-cell recognition, and may facilitate the design of clinical intervention strategies for autoimmunity based on the specificity of this recognition event.